How the Grid Works
Why every hour matters for clean energy — an interactive data story using EIA hourly generation data across America's grid regions
Why every hour matters for clean energy — an interactive data story using EIA hourly generation data across America's grid regions
Click a region to explore its unique energy story. Each region has a different generation mix and clean energy challenge.
Right now — this very second — grid operators are orchestrating a symphony of thousands of generators to deliver electricity to millions of homes, hospitals, data centers, and factories.
Every hour, they must perfectly balance supply with demand. The margin for error is razor-thin: even a small imbalance can cascade into blackouts.
What you see is every single hour of electricity generation in 2024 — 8,760 dots. Each one represents the grid's output during that hour.
Blue and green dots are the cleanest hours: nuclear, hydro, wind, and solar carried the load. Orange and red dots are the dirtiest: fossil generators were ramped to maximum.
The size of each dot reflects total generation — bigger dots mean more power flowing through the grid during that hour. Notice how they swell during summer peaks and shrink in the quiet overnight hours.
This is the electricity system that powers modern life. It's vast, variable, and always changing. And yet conventional carbon accounting treats every hour as though it were the same.
Scroll to discover why that assumption is dangerously misleading.
Nuclear and hydroelectric power form the grid's clean, firm foundation. They run 24/7/365 regardless of weather.
Look at the blue band — it barely moves. That's the steady, unwavering stream of carbon-free power that anchors the grid every single hour.
As demand climbs each morning, fossil generators ramp up. First efficient gas, then dirtier units: peakers, oil, coal.
The emission rate of every MWh changes dramatically by hour.
Wind and solar have transformed the grid. But they generate when nature allows, not when needed.
Summer midday: solar floods the grid. Winter evenings: almost nothing. The pattern is dramatic and seasonal.
The transition isn't just more renewables. It's reliable + affordable + clean.
Annual Scope 2 gives one number. It looks clean. Reassuring.
But behind that average hides chaos. Some hours are nearly zero-carbon. Others are heavily fossil-fueled.
A company "matched" at 100% annually may still cause emissions during thousands of hours.
Same grid. Two hours. Radically different resource mixes.
The clean hour is dominated by nuclear and renewables. The dirty hour has fossil fuels stacked high.
Hourly accounting reveals what annual numbers hide.
The transition: from reliable + affordable to reliable + affordable + clean.
Hourly matching tells markets: "We need clean power at 6 PM in January, not just sunny April afternoons."
This drives investment in firm clean power, storage, and demand flexibility.
Our Hourly Clean Energy Calculator estimates your hourly Scope 2 emissions using proposed GHG Protocol revisions.
Explore the Hourly Calculator →